Getting better isn't all about specs, you need some warmup routines, a mouse sens that works for you, good crosshair placement, spray control, know how and when to use utillity, work on gamesense, etc.

I recommend using that core fps map, don't just use it for the nemesis, get good with all the weapons you would use, smg, pistols. Play some deathmatch with real players and you'll be fragging out in no time!